Warp-tension equalization mechanism for travelling-wave shedding looms



Dec. 3, 1968 H. FEND WARP-TENSION EQUALIZATION MECHANISM FORTRAVELLING-WAVE SHEDDING LOOMS 5 Sheets-Sheet 1 Filed July 25, 1966INVENTOR.

H. FEND ALIZAT Dec. 3, 1968 WARP- SION E ION MECHANISM FOR T A ELLI AVESHEDDING LOOMS 5 SheetsSheet :2

Filed July 25, 1966 INVENTOR.

H. FEND WARP-TENSION EQUALIZATION MECHANISM FOR I Dec. 3, 1968TRAVELLING-WAVE SHELDING LOOMS 5 Sheets-Sheet Filed July 25, 1966INVENTOR. BYL),u-.A l/ M United States Patent 3,414,020 WARP-TENSIONEQUALIZATION MECHANISM FOR TRAVELLING-WAVE SHEDDING LOOMS Heinrich Feud,Uster, Zurich, Switzerland, assignor to Oerlikon-Buhrle Holding AG,Zurich, Switzerland Filed July 25, 1966, Ser. No. 567,607 Claimspriority, application Switzerland, June 27, 1965, 10,509/65 19 Claims.(Cl. 139--12) ABSTRACT OF THE DISCLOSURE A travelling-wave shedding loomhaving a number of heddle frames side by side and groups of warp threadsof a width corresponding to the width of the heddle frames. A warpthread tension device individually controls the warp tension of eachgroup of warp threads. Tension equalization means are arranged betweenthe tension devices and provide that the same force is extended by eachof the tension devices to produce the equal warp thread tension. Thistension equalization can be attained by cable hydraulic or pneumaticmeans.

Travelling-wave shedding looms (sometimes called wave-weaving looms)employing heddle frames encounter a problem not present withconventional looms, namely, the equalization of the warp tension betweentwo neighboring heddle frames. Since the heddle frames necessarilyassume different vertical posit-ions as required by the wave shape ofthe shed formation, there results, unless preventive measures are taken,a varying Warp tension in each heddle frame, in dependence on theinstantaneous position of the warp sheet. Because of the varyingtension, there arises in the neighboring regions of the interlacing edgea varying tension, which causes a step-like distortion of theinterlacing edge. This is a serious fault in weaving and causes,according to the interlacing, more or less pronounced stripes in theweaving pattern at the separation between heddle frames. There is alsothe danger that individual threads will slacken at this separation andcan be pulled from the shuttles.

It has been suggested to solve this problem by use of a resilienttension equalization device similar to the tension beam of conventionallooms, for each heddle frame width. The arrangement has the disadvantagethat the warp tension actually is not held constant, because the tensionof a spring increases with compression or stretching. Moreover, it isdiflicult simply to adjust all springs to the same tension.

Two embodiments of the invention will now be described in detail, withreference to the accompanying drawings, wherein:

FIG. 1 is a side view of a travelling-wave shedding loom incorporatingthe invention, with side panels removed;

FIG. 2 is a side view of the invention on expanded scale, taken alongline II--II of FIG 3;

FIG. 3 is a front view, partly in cross section, of the invention, takenalong line IIIIII of FIG 2;

FIG. 4 is a top view of the guide roller arrangement, with cover plateremoved; and

FIG. 5 shows a hydraulic equalization as a second form of the invention.

Referring to FIG. 1, the travellingwave shedding loom has a warp beam 11with a drive 12 and control gearing 13. The warp threads 14 run from thebeam over a guide roller 15 to the warp stop-motion device 16, fromwhich they continue to a tension equalization lever 17 and thence to theheddle frames 18, which form the shed 19 in which the shuttles 20 move.The reed 21 beats up the weft at the fell 22 of the fabric. The wovenfabric 23 continues over control and pressure rollers 24, 25 to thecloth beam 26, where it is taken up. The drive mechanisms for theshuttles and heddles are indicated by reference numerals 27, 28,respectively. The tension equalization mechanism is mounted on atransverse support 29, and a cable 30 runs from the mechanism to a lever31, to which it is fixed. The lever 31 turns on a pivot 32 which isfixedly mounted on the loom frame. A fluid piston 33, acted upon bycompressed air p and moving into a compressed-air cylinder 34 alsofixedly mounted on the loom frame, presses on the top surface of lever31. A lever 66 provides a control connection between lever 31 andcontrol gearing 13. The pressure in cylinder 34 can be held constant atany desired value.

FIGURES 2-4 illustrate the complete tension equalization mechanism onexpanded scale. There is one tension equalization lever 17 for eachheddle frame width. Each lever 17 carries an upper and lower crossarm,35 and 37, respectively, which terminate in disks 36, 38. A lever 17 ismounted by means of a sleeve 39 for pivoting on a continuous shaft 40,which, in turn, is mounted on the transverse support 29 by means of asupport 41.

A nose 42 of a lever 17 acts on an individual slide 43, which is held invertical position by a cover plate 44 and longitudinally guided by pins45, 46. The pins move in guide slots 47, 48 of plate 44 and rest with anen larged head on support 29. Pin 46 also serves as the support pointfor a movable grooved wheel 49.

The arrangement of the wheels is seen at FIG. 4. A series of pins 50 arefixedly mounted on the support 29, and serve together (in a manner notfurther illustrated) to secure the cover plate 44, which has beenremoved in FIG. 4 for illustrative purposes. Thus, the guide slots 47,48 are not shown. The pins 50 also serve as support points for a seriesof grooved wheels 51.

At the upper pin 45 of each of the first and last slide 43a a groovedwheel 52 is connected], the diameter of which is smaller than thediameter of the other grooved wheels 49. In the drawing, there isillustrated only the last slide 43a of these two slides. These slides43a are connected to the crossarms 35, which guide the Warp threads onthe edges of the fabnic. As there are guided on this first and lastcrossarm accordingto the width of the fabric more or less warpingthreads, but always less than on the other crossarms 35 the loading ofthe first and last crossarms 35 are less than of the others.

The sizes ofthe grooved wheels 51 and 49 are chosen so that the cablelength between the wheels 51 and 49 are parallel toone another, i.e. theangle of winding of the cable around the wheels 49 and 51 is exactlywhereas the angle of winding of the cable 30 around the wheel 52 issubstantially smaller. Whereas the angle of winding the cable 30 aroundthe wheel 49 depends on the position of the wheel 49, as the cablelengths are parallel to one another, the angle of winding of the cablearound the wheel 52 depends on the position of the wheel 52. The greaterthe force, which the warp threads exerts on the slides 43 and 43a thegreater the angle of winding and the greater the force, which the cable30 exerts on the wheel 52. Therefore the angle of winding the cablearound the wheel 52 depends on the number of warp threads, which areguided over the first and last crossarm 35. The cable 30 passes over thewheels 51 and under the wheels 49, 52.

The manner of operation of the tension equalization mechanism will nowbe described.

The warp threads 14, led over the pivotally mounted tension equalizationlever 17, are separated into groups by the disks 36, such that eachcrossarm 35 carries exactly the number of warp threads needed for thewidth of a heddle frame section. The warp threads, which are undertension, exert a forward pull on the lever 17, which bears with its nose42 on the slide 43. The slide acts on the cable 30 by means of the pin46 and wheel 49, and is responsible for a pull on the cable thatcorresponds to the warp tension.

All of the levers 17 act similarly on the cable, but the resulting cabletension is not equal to one-half of the slide force. It is thusimportant that individual slides can assume positions other than thoseshown, without, however, changing the force relationship.

When a shed is formed, the warp threads are shortened and the lever 17associated with that shed moves forward and is thus placed under aconstant reversely directed force from the cable 30, which, it isassumed, is pulled, at the end of the series of wheels (that is, at therighthand A), by a constant force obtained by compressed air or aweight, for example. The warp tension is thus not altered. But the levermovement does require an additional length of cable, which can beobtained either by drawing up the cable end or by an opposite movementof one or more neighboring levers 17.

In accordance with the invention, the constant pull can be applied toboth ends of the cable, or to only one end (as just described) and theother end either made fast to a stationary point, or preferably,connected to the end of the cable to which the force is applied.

Since the heddle movement is very quick and since the heddles along thefabric width are in diiferent positions of their movement at any givenmoment, the tension in the cable is equalized, although not necessarilyto the end wheels. The equalization is achieved despite the fact thatthe friction ratios cause a certain amount of damping. The cable tensionis also equalized when both ends A of the cable 30 are fixed. Anequalized warp tension is obtained between two neighboring levers and,indeed, over the entire width of the fabric for various positions of theheddles. Here the amount of the warp tension, which may be regulated byvariable braking of the Warp beam, for example, is of no consideration.Whatever the warp tension, the desired equalization is obtained.

In order to facilitate a quick equalization of the warp tension from onelever 17 to the next, the wheels 49, 51 have a center hole appreciablylarger than the pins 46, 51. Consequently, for short, quick movementsthese wheels roll on the surfaces of the pins, and only for the longermovements of the slides 43 do they slide over these surfaces. The warptension equalization compnises chiefly the former kind of movement,control of the warp let-off the latter.

Because the fabric width is not always exactly equal to the heddlewidth, it can occur that only part of the last heddle frame at a fabricedge is threaded and thus only part of the crossarm 35 of the lever 17for that heddle frame is occupied with warp threads. As a result, thislever would not be in balance with the others; because, although thesame cable tension acts on it as on the others, the warp tension shouldnot be greater here than anywhere else. To ensure that this lever is inbalance with the others, the wheel 52 of the corresponding slide 43 isheld by the upper pin 45, and has a smaller diameter and central holethan the wheels 49 held by pins 46. The cable 30 passes over the wheelat such an angle that the component of force, from the cable tensiontransmitted to the slide in its longitudinal direction is less than isthe case with the other slides. Since the warp tension remains constantand causes an equal oppositely directed force from the cable, the slide43a moves forward and wheel 52 assumes a position at which the twoopposed forces are equal. If the warp tension is great, the wheel 52takes, for example, the position 52' shown in broken line.

Since the tension in the cable and the warp are mutually influential,the cable 30 is not fixedly held at A, but is placed, at least at oneend, as already explained, under a definite tension obtained by means ofthe lever 31 (H6.

l) and compressed air cylinder 34. The pressure p of the compressed airfed the cylinder determines the warp ten sion. Weights of variousamounts hung from the cable end could be substituted for the lever 31and cylinder 34. The pressure p is generated by a compressor or a fluidpump and is held constant by a pressure reducing valve.

The position of lever 31 (or of the weights) can be sensed to provide acontrol of the warp beam 11. If too much warp should be payed out, alllevers 17 will move rightwards (FIGS 1, 2). The slides 43 with theirsheaves 49, urged by the tensed cable, move with the levers, leavingfree a certain length of the cable 30, which is pulled down by the lever31 under action of the piston 33. The change in position of the lever 31can then be used, in a manner not further illustrated or described, tocontrol the warp let-off gearing 13, which is adjusted to pay out lesswarp or, in the opposite case, more warp.

Referring to the embodiment shown at FIG. 5, a series of fluid pistons60 are arranged in a common hydraulic chamber 61 filled with asubstantially incompressible hydraulic fluid 62 and having a furtherpiston 63. The tension equalization levers 17, shown only schematically,bear on individual ones of the pistons 60. A lever 64, turning on apivot 65, acts on the piston 63. The lever is in physical contact withthe piston 33 and also connected to the lever 66, which acts on thegearing 13.

The form of the invention operates in the same way as the previous form.The fluid 62 exerts a constant pressure on the pistons 60 independent oftheir positions. All of the pistons together determine the position ofpiston 63 and thus the control of the warp let-off through gearing 13.The warp tension can be varied by changing the pressure p in cylinder34.

The illustration at FIG. 5 is purely schematic; therefore it is not tobe assumed that piston 63 necessarily is located approximately levelwith the pistons 69. As is obvious to one skilled in the art, the latteralong with their portion of the hydraulic chamber can be mounted on asupport having the same function and approximately the same location assupport 29.

Obviously, in the form of FIG. 5 weights could be substituted for thefluid cylinder 34 and the position of the weights sensed.

I claim:

1. In a a travelling-wave sheeding loom employing heddle frames, thecombination comprising a wrap tension equalization mechanism, comprisinga first spaced individual means for each heddle frame width section forsupporting and tensioning the wrap yarn associated with said width, saidfirst means being located upstream of the heddle frames, a sec-0ndmeans, cooperating with each of said first means, responsive to changesin the warp tension at any of said first means for substantiallyequalizing the warp tension at a neighboring first means, each of saidfirst means comprising a member mounted free to pivot in a planesubstantially parallel to the warp movement under influence of the warptension, the pivoting of said first means in the direction of movementof the warp tending to reduce the tension and in the opposite directiontending to increase the tension, said second means comprising individualfirst members movable back and forth in the direction of the warp forcontacting each of said first means for supporting it against the forceof the warp tension, said first members defining a plane. individualthird means associated with each of said first members and individualfourth means located between each first member and said second meansincluding a tensed fiexible means passing under each of said third meansand over each of said fourth means to describe a serpentine path lyingin a plane substantially parallel to said plane of said first members,whereby the tension in said flexible means exerts on each of said thirdmeans an equal force equal and opposite to that of the warp tension oneach of said first means.

2. The combination according to claim 1 wherein said third and fourthmeans are wheels having a central opening lying substantially in acommon plane parallel to said plane of the first members including asupport extending transversely to the warp; a first pin for each of saidfourth means mounted on said support and located in said opening forpermitting the associated wheel to roll and slide over the lateralsurface of the pin and a second pin for each of said third means,mounted on individual ones of said first members and located in saidopening, for permitting the associated wheel to roll and slide over thelateral surface of the pin.

3. The combination according to claim 2, wherein said force exerted bysaid flexible means on said third means of a first member at an edge ofthe fabric woven is less than that exerted on the other of said thirdmeans.

4. The combination according to claim 3 wherein the contact between saidflexible means is nearer said first means for said fourth means than forsaid third means and nearer for said third means associated with a firstmember at an edge of the fabric than for those third means associatedwith the other of said first members.

5. The combination according to claim 4, wherein said flexible meansruns towards and from said third means of a first member at an edge ofthe fabric at an acute angle to the direction in which said member movesand runs towards and from said third means of the other of said firstmember substantially parallel to the direction in which said membersmove.

6. In a travellingwave shedding loom having at least three heddle framesarranged side by side moved one after another, a warp beam havingseveral groups of warp threads, each group being associated with aheddle frame, the combination comprising a warp thread tension devicefor each group of warp threads, comprising each a first and a secondturn off wheel, a pivoted lever on which said wheels are mounted, atension equalization device for the mutual equalization of the threadtensions of all said warp thread groups, comprising members engagingsaid levers and means for automatically distributing and exerting duringloom operation an equal force to all of said members for the mutualequalization of the thread tensions.

7. The combination according to claim 6 wherein said levers pivot in aplane substantially parallel to the warp movement under the influence ofwarp tension, the pivoting of said levers in the direction of movementof the warp tending to reduce the tension and in the opposite directiontending to increase the tension.

8. The combination according to claim 6 wherein each of said leverssupports an upper and a lower cross arm over which the warp passestowards the heddle frames.

9. The combination according to claim 6 including a fifth meanscooperating with said second means for bold ing the warp tensionsubstantially at a desired value for all positions of the heddle frames.

10. The combination according to claim 9, wherein said second meansincludes an individual first member movable back and forth in thedirection of the warp for contacting each of said first means forsupporting it against the force of the warp tension, said first membersdefining a plane; in individual third means associated with each of saidfirst members and an individual fourth means located between each firstmember and wherein said second means further includes flexible meanspassing under each of said third means and over each of said fourthmeans to describe a serpentine path lying in a plane substantiallyparallel to said plane of the first members, said fifth means subjectingsaid flexible means to a constant tension, whereby said flexible meansexerts on each said third means an equal and constant force equal andopposite to that of the warp tension on each of said first means.

11. The combination according to claim 10, wherein said third and fourthmean-s are wheels having a central opening lying substantially in acommon plane parallel to said plane of the first members; and includinga support extending transversely to the warp; a first pin for each ofsaid fourth means, mounted on said support and located in said opening,for permitting the associated wheel to roll and slide over the lateralsurface of the pin; and a sec-ond pin for each of said third means,mounted on individual ones of said first members and located in saidopening, for permitting the associated wheel to roll and slide over thelateral surface of the pin.

12. The combination according to claim 11, wherein said force exerted bysaid flexible means on said third means of a first member at an edge ofthe fabric woven is less than that exerted on the other of said thirdmeans.

13. The combination according to claim 12, wherein the contact betweensaid flexible means is nearer said first means for said fourth meansthan for said third means and nearer for saidthird means associated witha first member at an edge of the fabric than for those third meansassociated with the other of said first members.

14. The combination according to claim 13, wherein said flexible meansruns towards and from said third means of a first member at an edge ofthe fabric at an acute angle to the direction in which said member movesand runs towards and from said third means of the other of said firstmember substantially parallel to the direction in which said membersmove.

15. The combination according to claim 10, wherein said flexible meanshas first and second ends and said fifth means includes a fluid pistonunder an adjustable constant pressure and acting on one end of saidflexible means.

16. The combination according to claim 10, wherein said flexible meanshas first and second ends and said fifth means includes a weight ofadjustable size hung from one end of said flexible means.

17. The combination according to claim 6, including an individual firstfluid piston acting on each of said first means in a direction tosupport the latter against the force exerted on it by the warp tension,each said piston being under the same hydraulic pressure; a secondpiston in hydraulic communication with said first pistons acted upon byan adjustable constant force for causing the hydraulic pressure actingon said first pistons.

18. The combination according to claim 17, including a fluid pistonacting on said second piston to produce said force.

19. The combination according to claim 9, wherein the position of saidfifth means varies in dependence on the tension exerted on said flexiblemeans; and means responsive to the position of said fifth means forcontrolling the let-off control gearing of the loom.

References Cited UNITED STATES PATENTS 2,433,190 12/1947 Ancet 139-132,679,264 5/1954 Dunod 139--13 2,988,113 6/1961 Smiley 13997 3,147,7769/1964 Hofmann 139-1 14 FOREIGN PATENTS 240,564 8/ 1962 Australia.559,047 9/ 1932 Germany.

OTHER REFERENCES Haberhauer: German App. No. 1,072,659, Pub. 1960.

HENRY s. JAUDON, Primary Examiner.

